The present invention relates to an automatic speed sensor positioner for an automotive vehicle, and more particularly to a vehicle wheel speed sensor which is automatically and positively adjusted by the assembling of the wheel on the axle.
Modern anti-skid control systems operate on the basis of electrical signals which indicate the angular velocity of one or more of the vehicle wheels. These signals are generally derived from an electromagnetic sensor, including a magnet mounted on a stationary part of the vehicle, such as the axle housing, and a slotted or notched metal ring or rotor which rotates with the wheel opposite the magnet. As the openings or discontinuities in the rotor pass the magnetic poles of the sensor, the resultant flux variations produce a signal, the frequency of which is a function of the angular velocity of the wheel.
To provide the necessary accuracy of the velocity signal for use in a brake control system, the sensor and rotor must be precisely positioned with respect to each other during assembly of the wheel on the axle and must remain in the adjusted relationship during use, even after extended operation in which the components are subjected to road shocks and constant vibration, and must be protected from dirt, mechanical damage and heat.
Among the objects of the present invention is the provision of a novel automatic sensor positioner for a vehicle wheel speed sensor in which the rotating and stationary components of the sensor mechanism are automatically adjusted to a precise relationship when the wheel is mounted on the axle and maintained in that relationship during vehicle operation.
Another object of the present invention is the provision of a novel automatic sensor positioner for a wheel speed sensor wherein the rotor is mounted on the vehicle wheel and the magnetic sensor is mounted on the stationary axle structure in a housing. The housing and magnetic sensor have cooperating tapered or inclined surfaces to frictionally retain the sensor in its adjusted position, with a spring applying a regulated force to urge the tapered surfaces into frictional engagement. The sensor can be easily repositioned in the housing through the use of a simple tool.
The present invention also comprehends a sensor mechanism including a magnetic sensor, a housing for the sensor that is mounted on a stationary portion of the vehicle, such as the axle, and an ablative plate operatively mounted on the front face of the magnetic sensor and having an opening to expose the magnet pole pieces. The ablative plate is utilized to accurately space the sensor from the rotor.
Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.